Viagra linked to increased melanoma risk

A new study has found that the use of the erectile dysfunction drug Viagra (sildenafil; Pfizer) is linked to an increased risk for melanoma, a deadly form of skin cancer

Robin Wulffson, MD

A new study has found that the use of the erectile dysfunction drug Viagra (sildenafil; Pfizer) is linked to an increased risk for melanoma, a deadly form of skin cancer. The study was published online on April 7 in the journal JAMA Internal Medicine by researchers at Harvard Medical School in Boston, Massachusetts.

The study group comprised 25,848 men who were enrolled in the Health Professionals' Follow-up Study (HPFS) and were followed from 2000 through 2010. The investigators note that they decided to conduct the study based on earlier studies that reported that that phosphodiesterase 5A (PDG5A) inhibitors, including Viagra, may stimulate the synthesis of the skin pigment melanin; increased melanin synthesis has been linked to increase melanoma risk. Furthermore, studies have reported a link between Viagra use and other PDG5A inhibitors to promotion of melanoma cell invasion, particularly in men who carry a mutation in the BRAF gene.

In the 2000 biennial survey, the study participants were asked whether they had been treated or were being treated for erectile dysfunction. Among the 25,848 men, 1,378 (5.3%) reported taking Viagra in the previous three months and 1,618 (6.3%) reported that they had taken the drug at least once. Not surprisingly, these men tended to be older than the entire HPFS study group (66.1 years vs. 64.8 years). They were also more likely to be obese and to have a history of severe or blistering sunburns; however, they reported less sun exposure during adult life.

Since 1986, the study participants had been reporting diagnoses of melanoma, and other forms of skin cancer: squamous cell carcinoma and basal cell carcinoma. During follow-up from 2000 through 2010, 142 cases of melanoma occurred, 580 cases of squamous cell carcinoma occurred, and 3,030 cases of basal cell carcinoma occurred.

The investigators found that recent Viagra users were significantly more likely to be diagnosed with invasive melanoma than nonusers. Men who had taken Viagra at least once also were found to have an increased risk for melanoma. In contrast, neither group of Viagra users had an increased risk for squamous cell carcinoma or basal cell carcinoma. The data was adjusted for a number of factors, including age, body mass index (BMI), tobacco use, physical activity, and childhood reaction to sun; the data was also adjusted for melanoma risk factors, such as mole count, hair color, and family history. The risk associated with Viagra use was 81 cases per 100,000 person-years (216.4/100,000 for users and 135.4/100,000 nonusers).

The study did not include other PDG5A inhibitors, such as tadalafil (Cialis; Eli Lilly) and vardenafil (Levitra; GlaxoSmithKline), because they were not FDA approved when the study began. The researchers noted, however, despite those drugs not being included in the study, the link between Viagra and melanoma might be partly due to the later use of Cialis and Levitra among recent Viagra users. They noted that Cialis and Levitra had a longer clearance time (time for the drug to be cleared from the body); thus, they could have contributed to the increased risk of melanoma associated with Viagra.

They concluded that their findings should be interpreted cautiously and are insufficient to alter current clinical recommendations. However, they noted that the study results provide epidemiological evidence of possible skin adverse effects of PDE5A inhibitors. They recommended that further research be conducted.

Take home message:

Users of Viagra and possibly other erectile dysfunction drugs, may be at increased risk for melanoma. Therefore, they should limit sun exposure and use sunscreen. This is particularly important in Sunbelt regions such as Southern California.

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Robin Wulffson is a California native and a graduate of the UCLA School of Medicine. He is a Diplomate of the American Board of Obstetrics and Gynecology and a Lifetime Fellow of the American Board of Obstetrics and Gynecology. He served as a battalion surgeon with the 2/77th Artillery, 25th Infantry Division in Vietnam; he was awarded a Bronze Star and a Purple Heart. Following his specialty training, he practiced obstetrics and gynecology in Orange County, California for 25 years. In addition to his medical and military background, he has a keen interest in technology, including automobiles. Since 1998, he has done freelance writing in the healthcare field. He has published two novels, which feature a strong female protagonist: An Improbable Cause and Avalon. Dr. Wulffson resides with his family in Tustin, California.